The present invention relates to a diyne-containing (co)polymer, processes for producing the same, and an insulating film. More particularly, the invention relates to a diyne-containing (co)polymer which is soluble in organic solvents, has excellent processability, and gives a cured coating film excellent in heat resistance, solvent resistance, mechanical strength, and low-dielectric characteristics and which is suitable for use as a material for, e.g., a low-dielectric interlayer insulating film for semiconductor elements such as LSIs, system LSIs, DRAMs, SDRAMs, RDRAMs, and D-RDRAMs, a surface coat film or another protective film for semiconductor elements, a low-dielectric interlayer insulating film for multilayered circuit boards, a protective film or insulating film for liquid-crystal display elements, and a gas separation membrane. The invention further relates to processes for efficiently producing the diyne-containing (co)polymer and to a cured film obtained by curing the (co) polymer.
In the field of electronic materials, the recent progress toward a higher degree of integration, a larger number of functions, and higher performances has resulted in increased circuit resistance and increased capacitance between circuits and this in turn has resulted in increases in power consumption and delay time. In particular, an increase in delay time is an important factor contributing to a decrease in signal transfer speed in devices and to the occurrence of cross talk. Because of this, it is desired to reduce parasitic resistance or parasitic capacitance in order to reduce the delay time and thereby attain higher-speed device operation. One measure which is being taken in reducing the parasitic capacitance is to coat the periphery of a circuit with a low-dielectric interlayer insulating film.
Interlayer insulating films are required not only to have excellent heat resistance so as to withstand high-temperature steps in the production of printed circuit boards, such as the step of thin-film deposition and steps conducted after chip connection, pin insertion, etc., but to have chemical resistance so that they withstand wet processing. Furthermore, copper wirings, having lower resistance, are recently coming to be employed as a substitute for aluminum wirings and, with this trend, planarization by CMP (chemical mechanical polishing) has become common. Interlayer insulating films are hence required to have mechanical strength so as to withstand this processing.
The invention has been achieved in view of the desires described above.
One object of the invention is to provide a diyne-containing (co)polymer which is soluble in organic solvents, has excellent processability, and gives a cured coating film excellent in heat resistance, solvent resistance, low-dielectric characteristics, and mechanical strength and which is suitable for use as a material for, e.g., a low-dielectric interlayer insulating film for semiconductor elements such as LSIs, system LSIs, DRAMs, SDRAMs, RDRAMs, and D-RDRAMs, a surface coat film or another protective film for semiconductor elements, a low-dielectric interlayer insulating film for multilayered circuit boards, a protective film or insulating film for liquid-crystal display elements, and a gas separation membrane.
Another object of the invention is to provide processes for producing the (co)polymer.
Still another object of the invention is to provide a cured film.
The present inventors made intensive investigations in order to develop a polymer suitable for use as a material for insulating films or protective films and to thereby satisfy the desires described above. As a result, they have found that a novel polymer having specific repeating units in an amount not smaller than a specific value in mol % is suitable for those applications.
This novel polymer was found to undergo the Bergman cyclization at the specific repeating units upon heating to generate aryl radicals. Namely, this polymer was found to be crosslinked at a low temperature to accomplish those objects.
The invention has been completed based on this finding.
The invention provides the diyne-containing (co)polymer, processes for producing the same, and cured film described below.
[1] A diyne-containing (co)polymer which contains at least 10 mol % repeating units represented by the following formula (1) and has a weight-average molecular weight of from 500 to 1,000,000:
"Brketopenst"Cxe2x89xa1C"Parenopenst"Y"Parenclosest"nCxe2x89xa1Cxe2x80x94Ar"Brketclosest"xe2x80x83xe2x80x83(1)
wherein Y represents a bivalent organic group represented by the following formula (2) or (3); Ar represents a bivalent organic group; and n represents 0 or 1; 
wherein R1 and R2 may be the same or different, are located in the cis positions, and each represents a hydrogen atom, an alkyl group, or an aryl group; 
wherein R3to R6 may be the same or different and each represents a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group, or an aryl group.
[2] A process for producing a diyne-containing (co)polymer which comprises polymerizing (A1) at least one member selected from the group consisting of compounds represented by the following formula (4) and compounds represented by the following formula (5) with (B1) at least one compound represented by the following formula (6): 
wherein X1 and X2 may be the same or different, are located in the cis positions, and each represents a halogen atom; and R7 and R8 may be the same or different and each represents a hydrogen atom, an alkyl group, or an aryl group; 
wherein X3 and X4 may be the same or different and each represents a halogen atom or xe2x80x94SO3R9, wherein R9 represents an alkyl group, a fluoroalkyl group, or an aryl group; and R10 to R13 may be the same or different and each represents a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group, or an aryl group;
HCxe2x89xa1Cxe2x80x94Arxe2x80x2xe2x80x94Cxe2x89xa1CHxe2x80x83xe2x80x83(6)
wherein Arxe2x80x2 represents a bivalent organic group.
[3] A process for producing a diyne-containing (co)polymer which comprises polymerizing (A2) at least one member selected from the group consisting of compounds represented by the following formula (7) and compounds represented by the following formula (8) with (B2) at least one compound represented by the following formula (9): 
wherein R14 and R15 may be the same or different, are located in the cis positions, and each represents a hydrogen atom, an alkyl group, or an aryl group; 
wherein R16 to R19 may be the same or different and each represents a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group, or an aryl group;
X5xe2x80x94Arxe2x80x3xe2x80x94X6xe2x80x83xe2x80x83(9)
wherein X5 and X6 may be the same or different and each represents a halogen atom or xe2x80x94SO3R20, wherein R2 represents an alkyl group, a fluoroalkyl group, or an aryl group; and Arxe2x80x3 represents a bivalent organic group.
[4] The process for producing a diyne-containing (co)polymer described in [2] or [3] above wherein the polymerization is conducted in the presence of a palladium catalyst and a basic compound.
[5] A process for producing a diyne-containing (co)polymer which comprises oxidatively polymerizing at least one compound represented by the formula (6) described above.
[6] A cured film obtained by curing the diyne-containing (co)polymer described in [1] above.
The diyne-containing (co)polymer of the invention is soluble in organic solvents and can have improved processability, because it has specific repeating units in an amount not smaller than a specific value in mol % and has a specific weight-average molecular weight. Furthermore, when the (co)polymer is applied and cured, the cured coating film can be improved in heat resistance, solvent resistance, and low-dielectric characteristics. The diyne-containing (co)polymer of the invention can be cured by a method in which the Bergman cyclization is utilized to generate aryl radicals on the polymer backbone. Thus, the diyne-containing (co)polymer can be efficiently crosslinked and cured at a low temperature. Moreover, the cured film of the invention is excellent in heat resistance, solvent resistance, mechanical strength, and low-dielectric characteristics.